CAUSED BY STRESS AND REGULAR TOOTHPASTES...USE NATURAL INGREDIENT TOOTHPASTE CUT BACK ON Sugar CAFFEINE AND SWEETS...IF YOU START TO GET A THICK TOUNGUE AND A METALLIC TASTE IN MOUTH YOU CAN BET YOU ARE GETTING A FLAREUP AND YOU NEED TO DRINK LOTS OF WATER AND NO CAFFEINNE! LOOK UP LICHEN PLANUS ON LINE (STAY AWAY FROM INDIA SIGHTS...THEY ARE TRYING TO SELL EXPENSIVE PRODUCT NOT GIVE OUT INFO)